Chapter 8.2, Problem 51E

38. $\begin{array}{l}\frac{dx}{dt}=4x+5y\\ \frac{dy}{dt}=-2x+6y\end{array}$

39. X′ = $\left(\begin{array}{cc}4& -5\\ 5& -4\end{array}\right)$X

40. X′ = $\left(\begin{array}{cc}1& -8\\ 1& -3\end{array}\right)$X

Find phase portraits for the systems in Problems 38, 39, and 40.